Spontaneous Peroneal Entrapment Neuropathy due to Anatomic Abnormality of Proximal Tibiofibular Joint：A Clinical Study of 10 Cases

Abstract Background: Dislocation or instability of the proximal tibiofibular joint is often obscure, difficult to diagnose, easily overlooked by clinicians, and may be the cause of some unexplained cases of common peroneal nerve compression. Moreover, the literature on proximal tibiofibular joint dislocation is very limited, with only a few case reports. This study aimed to evaluate the morphological characteristics and anatomic variation of tibiofibular joint through preoperative auxiliary examination and intraoperative exploration and to discuss its clinical significance.Methods: From October 2015 to July 2021, a common peroneal nerve palsy diagnosis was made for 243 patients in our institution, of whom 10 were diagnosed with unexplained common peroneal nerve palsy. We carefully compared the results of intraoperative exploration with anteroposterior and lateral radiographs of the patients’ lower limbs and CT of their lower limbs to investigate the presence of bony structural abnormalities. Results: In the examination of lower limb CT, we found that the anatomical relationship of tibiofibular joint was significantly abnormal in three patients, among whom the preoperative CT plain scan of the lower limbs indicated that the fibula position of the affected limb was 2 cm lower than that of the opposite side in one typical patient. In one of the three patients with abnormal CT results, high common peroneal tension was found even after releasing the thickened fibers at the fibula head. The compression factor of this patient was the anatomic variation of the tibiofibular joint, which led to the common peroneal nerve being pulled downward by the fibular head; thus, peroneal osteotomy was performed during the operation. After osteotomy, the common peroneal nerve was markedly reduced in tone.Conclusions: Anatomic abnormalities or dislocation of the proximal tibiofibular joint may result in the entrapment of the common peroneal nerve. Preoperative CT examination of these patients is required to determine the presence of common peroneal nerve compression due to bony structural abnormalities. If the patient has a definite bony structural abnormality, peroneal osteotomy may be required at the time of peroneal nerve release.